The present invention is generally directed to water heaters and more particularly pertains to enhancing the ability of a water heater to supply hot water.
Water heaters are typically controlled so as to limit the temperature of water contained therein to about 140.degree. F. with the intent to reduce the likelihood of accidental scalding at the point of usage. While such a low set temperature may reduce the likelihood of injury, it does compromise the ability of a water heater of a given size to supply hot water. The heating capacity of most water heaters cannot keep up with the continuous withdrawal of hot water. As cold water replaces the hot water withdrawn from the heater, the temperature of the water within the water heater will gradually drop off thus reducing the output water temperature. The ability of a water heater to quickly recover its set temperature is further aggravated by the fact that the burner is not activated until the temperature of the water drops well below its set temperature. In order to reduce unnecessary cycling, the gas valve that controls the flow of gas to the burner is typically configured to maintain the water temperature within.+-.12.degree. F. As a result, a significant drop off of the water temperature will have occurred before the water heater even begins to heat the water.
Efforts to increase the ability of a water heater to satisfy the demand for hot water without raising the set temperature, have previously been limited to increasing the volume of the tank, increasing the heating capacity of the burner or both. However, the size of the space dedicated for the installation of a water heater in most residential applications limits the maximum size of the water heater. Moreover, a water heater with a larger tank and possibly a larger burner would significantly increase the cost of the water heater.
A water heating system is needed which is capable of providing an increased amount of hot water for a given tank volume and burner size without increasing the temperature at which the hot water is delivered. Additionally, it would be most advantageous for such system to be adaptable to existing water heater configurations and further to be retrofitable to existing water heaters.